Drafting frame



April 15, 1958 R. WILDBOLZ DRAFTING FRAME 2 Sheets-Sheet 1 Filed July10, 1953 INVENTOR. M ILD BOLZ.

RUDOLF' BY A TTOK/VEK ite A DRAFTING FRANE Rudolf Wildbolz, Winterthur,Switzerland, assignor to Job. Jacob Rieter & C0., Ltd, Winterthnr,Switzerland, a corporation of Switzerland Application July 10, 1953,Serial No. 367,281 7 Claims priority, application Switzerland July 28,1952 Claims. c1. '19-.6

in this manner is irregular; it varies between the length of the tearingfield and zero. Such yarns and fabrics produced therefrom shrink duringfinishing operations because of excessive elongation during the tearingprocess, which is undesired with certain fabrics.

In order to overcome these difiiculties, it has been proposed to assistbreaking of the fibres in the filament bundle between the clampingroller pairs by providing special devices in the drafting frame. Thesedevices operate according to the principle of sharply diverting themoving filament bundle from its straight course in the drafting frame inorder to break the filaments at the point of diversion by an edgingeffect, depending on the gripping action of the front roller, at muchless tension than when breaking the filaments by apure tearing process.Staple fibre yarns produced in this manner have much less ability toshrink and have a more uniform staple than yarns produced by a puretearing efiect.

Numerous tests have shown that the filament ribbons or tows to be spunbehave differently during the breaking process depending on thematerial, manufacture, and avivage. Whereas some tows produce faultlessyarns at a certain diversion by the cutting or breaking means,characterized hereafter by the breaking angle, the longitudinal steppingof the broken individual fibres .isunsatisfactory with the same draftingframe arrangement. At a sharp deflectionof the filament ribbon, i. eat asmall breaking angle, little tension is needed to break the filaments atthe point of diversion. The staple obtained in this manner isextremelynniform but there is the danger of'breaking the filaments inpacks. Responsible for this are, besides the reasons. already mentioned,circumstances depending on .thecondition of the incoming ribbon, forexample periodic changes of .the .titre, twisted, crossing, or coheringfilaments. Since, whenever a whole.filament pack is broken, a period oftime elapses, .which is exactly definedby the draft in the draftingframe, untilthesimultaneously broken filaments are gripped by the frontroller and are again simultaneously broken, a thread is producedwhosecross section changes periodically. If one operates with a greaterbreaking angle, 'i. e. with less diversion ofthe tow at'the breakingdevice, a greater tension is needed 'in orderto break theindividualfilaments. Changes'of the ductility and of the sensitivity to crushingof the int'iividual filaments in the tow have therefore a much greatereffect, causing a greater percentage of filaments :to break outside ofthe point of diversion at the breaking device because of-the greatbreaking elongation and the greaterx'stress. The pro-j duced staple istherefore not as uniform. as at a; smaller 'breakangle, however, itsisof .much :better quality Ethan that produced by the pure tearingiPIOCGSS. x'z-Periodic Sttes atent ice changes of the cross section ofthe yarn, which may be caused by breaking the filaments in packs,disappear quickly, because the breaking zone is not exactly localized atthe diversion point. However, the shrinkability of the produced threadincreases.

It is evident from the above that the provisions to be made for treatinga spinning cable in a drawing frame comprising a breaking device,considering the tearing force, uniformity and shrinkability of thestaple fibre yarn, partly contradict each other.

Great tearing force, i. e. uniform staple and little shrinkability callfor small break angles, i. e. a sharp diversion of the filament ribbonat the breaking device. With this arrangement the danger of breakingwhole filament packs increases, impairing uniformity of the yarn.

On the other hand, the staple becomes less uniform and the tearing forceis less at a great break angle. This, however, makes the end productless uniform.

The drafting frame according to the invention overcomes thesedifliculties by providing means for changing the breaking angle of thefilament bundle at the breaking device without changing the distance ofthe breaking device from the front roller pair. Adjustability of thebreaking angle is preferably effected by means of aguide rail whoseposition can be changed.

The drafting frame according to the invention can be adjusted to producea staple fibre yarn of a desired quality, depending on the material,manufacture and avivage of the tows.

The invention is illustrated, by way of example, in the accompanyingdrawing in which Fig. 1 is a schematic sectional View of a breakerdrafting frame.

Figs. 2 and 3 are perspective illustrations of two modifications of adetail of the drafting frame shown in Fig. 1.

Figs. 4 to 6 are schematic sectional views of three modified breakerdrafting frames according to the invention.

Fig. 7 is a uniformity diagram of a faulty staple fibre yarn.

Fig. 8 is a uniformity diagram of a staple fibre'yarn produced on abreaker drafting frame according to the invention.

Like parts are designated by like numerals in different figures of thedrawing.

Referringmore particularly to Fig. l of the drawing, the breakerdrafting framecomprises front and rear bottom cylinders .1, 2, 3 onwhich rest top rollers .4 and '5 provided with an elastic covering.Thelcircumferential :speed .of the cylinders 1 and 2, 3 corresponds :tothe desired draft. The front top roller 4 is provided with pressuremeans, not shown, the back top" roller acting 'byits weight, .A shaft 6carrying a knife roller 7 is placed belowicylin der -3. Adiverting rail8 is arrangedabove the 'shaft T he knives 10f the rollers 7 have edges 9.which are .rearwardly inclined with "respect to the direction of theirmovement' The circumferential speed of theknife edges is 'greaterthan'that of the-delivery rollers 1, 4-; Gliding of-the filaments onthe'edges 9 has a continuous sharpeningefieet; The shaft 6andthedive'rting rail 8 extend-over the whole machine and are-supportedbythe bearing shields for the cylinders 2 and fif The rail 8 is providedwith polished diverting plates-i=1 for diverting the tows. A singleplate extending across the whole system may 'be provided instead ofindividual plates. i i H '7 1 Figure 2 is a detail illustrationof thesupport of the diverting rail 8. The bearing-shields 1 are pr'oviderlwith slots 12in which the rails '33 are sli'dable. Thelatter areprovided with, pins :13 extending intol'inclined :slots 14 of angleirons 15 which extend into the slots 12 and which are bolted to thebearing shield 10 (see holes 16). The angle irons 15 limit the lateralplay of the rails 8 in theslots12. A polished diverting plate 11 isprovided .on the rails for each spinning unit for supporting anddiverting the tow 17. g

Fig. 3 illustrates a modification of the support of the diverting rail8. The bearing shields 10 are provided with slots 12 in which the rail 8is movably guided andpositioned by wedges 18.nfiording changing theelevation of the rail; A polished diverting plate 11 for diverting andsupporting the tow 17 is provided on the rail for each spinning unit.

A belt 23 supportsQtlie broken staples 19 within the drafting field; Thebelt is laid around the cylinders 20,

'21 and the'ten'sioning roller 22, one or more slip rollers 24 rotatingon the belt. ,A rod 25 is placed at the inlet of the drafting frame andextends over the whole machine,

the rod carrying plates26 provided with thread spreading pins 27, eachpin extending over' two spinning units. Numeral 28 designates a towbobbin from which the tow 17 runs into the drafting frame.

'For starting operation of the drafting frame, the end of the tow 17 ispulled from the bobbin 28 and fibrillated so that the individual ends ofthe filaments are uniformly staggered in the tow. This may be done bymeans of sand paper. Thereupon the so prepared end of the tow is laidaround the rod 25 and the spreading pins 27, as well as around thecylinders 2 and whereupon the tow enters the'drawingfield from the nipof the cylinders 3 and 5. The end of the towpasses over the divertingplate 11 and under the knife roller 7 and thereupon, supported andguided by means of the belt 23 and the slip roller 24, into the nip K ofthe rollers 1 and 4. The breaking device 7 rotates in the direction ofthe movement of the filaments. The belt 23 is driven in the samedirection and so that it moves at least faster than the circumferentialspeed i of the rear cylinder 3. Ends of filaments whichproject from thetow are thereby continuously straightened. As soon as individualfilaments of thetow 17 reach the nip K, they are tensioned according tothe adjusted draft and are deflected exactly at the edges 9 of the kniferoller 7.. The extent of the deflection of the filaments is defined bythe breaking angle, i. e. the angle formed by the line connecting thepoint of deflection A at an edge 9 and the nip K, and the lineconnecting point A and the diverting point U at the diverting plate 11.Upon reaching breaking stress, the filaments break at the most stressedpoint, because of edging at point A, and are pulled as. staple fibres 19by the front cylinder pair 1, 4 and are subsequently spun by twistingmeans, not shown. For the reasons explained at the beginning of thisspecification not every tow can be worked without fault and at bestoperating conditions at the same breaking angle. The most suitable anglemust be found by experiment. This is preferably done, for example, bypulling the diverting rail 8 (Fig. 3) at first to its extreme rightposition whereby the rail with its diverting plates 11 is moved into itsmost elevated position by the illustrated means. In this position thebreaking angle ;KAU is smallest and a little shrinkable and uniformlystapled yarn is produced because of insignificant overtensioningofthe-staples. If examination in, a uniformity testing machine revealsperiodic changes of the cross section of the yarn, the diverting rail 8must be pushed somewhat to the left, i. e. lowered so that the breakingangle is enlarged. Fig. 7 shows a characteristic example of excessivevariations; The aforedescribed correction, however, makes the staplesless uniform and makesv the produced yarn more shrinkable. If a secondexamination shows that a uniform yarn, free of periodic changes (Fig.8), is produced, production can .be started on the machine, otherwise asecond adjustment must be made in the same direction.

The drafting frame according to the invention cannot only be adapted tothe available tow, but can also be adjusted to control shrinkability ofthe yarns produced from certain materials, within wide limits, dependingon the intended use of the yarns.

In contradistinction to the arrangement according to Fig. 1, the backtop roller 5 of the drawing frame shown in Fig. 4 rests on the cylinder3 and on the belt cylinder The longitudinally movable diverting rail 8is replaced by a diverting rail or plate member 40 which is swingabletransversely to its longitudinal axis. The diverting rail extends overthe length of a whole system and has at each end a swing arm 29 whicharms are supported by the cylinder 3 and serve for moving the divertingrail for a certain distance around the cylinder axis. The position ofthe diverting rail for producing the smallest breaking angle is shown indotted lines in Fig. 4. The arms 29 can be fixed in the'desired positionby tightening bolts 31 which extend through an arcuate slot 3th in thebearing block 32.

A third modification of the drafting frame is shown in Fig. 5. Adiverting roller 33 supported by swing levers 29' is provided instead ofthe diverting rail 40 of Fig. 4.

The mechanism for positioning the diverting roller is the same as thatfor positioning the rail 40 in Fig. 4.

Starting and operation of the drawing frames according to Figs- 4 and 5is the same as that of the drawing frame shown in Fig. 1. In order tochange the breaking angle KAU, the bolts 31 of each system are loosenedand the swing arms 29 or 29 are moved into the position corresponding tothe desired position of the diverting rail 40 or of the roller 33.Thereupon the bolts 31 are tightened.

Fig. 6 illustrates a fourth modification of the breaker drafting frameaccording to the invention in which the back-top roll 34 forms aclamping nip with the belt cylinder 21.. The purpose of the divertingmeans shown in Figs. 1 to 5 is achieved by changing the position of theshaft 6 for supporting the knife rollers 7' relatively to the stationarybearing block 35. The shaft 6' is supported by bearer plates 36 providedwith slots 38, bolts 37 extending through the slots 38 for fixing theplates 36 to the blocks 35.

In order to change the breaking angle KAU, formed by the nip K of thefront cylinders 1 and 4, the deflection point A at the severing means 7,and the nip U of the rear cylinders 21 and 34, the bolts 37, areloosened at all blocks 35 whereupon the bearer plates 36 for the shaft6' can be displaced perpendicularly to the plane of the drafting frameto produce the desired breaking angle and the bolts 37 are tightened.Starting and operation of the drafting frame according to Fig. 6 iseffected in the same manner as of the drafting frame shown in Fig. 1.

While I have shown and described specific embodiments of my invention,it will be apparent to those skilled in the art that various changes,modifications, substitutions, additions and omissions may be madetherein without departing from the spirit and scope of my invention asset forth in the appended claims.

I claim:

1. A drafting frame comprising, in combination, feed rollers, deliveryrollers, breaking means interposed between said feed and deliveryrollers, means for holding said breaking means in a permanentlyunchangeable position relatively to said delivery rollers, for producinga staple fibre ribbon from a filament bundle, guide means 76 platemember, said adjusting means being connected with said rail and adaptedto change the position of said rail relatively to said breaking means.

3. A drafting frame as defined in claim 1, said guide means including aguide roller supporting the filament bundle, a diverting plate memberspaced from and placed substantially parallel to the surface of saidguide roller and holding the filament bundle on said roller, saidadjusting means being connected with said plate member and adapted tochange the angular position of said plate member relatively to saidguide roller.

4. A drafting frame as defined in claim 1, said breaking means includinga belt supporting said filament bundle and a knife roller placedopposite to said belt and rotating at a circumferential speed greaterthan that of said delivery rollers, the edges of the knives of saidknife roller being 15 2,221,869

inclined rearwardly with respect to the direction of theircircumferential movement for producing a stroking action on the filamentbundle.

5. A drafting frame comprising, in combination, feed 10 the draftingoperation.

References Cited in the file of this patent UNITED STATES PATENTS HalinNov. 19, 1940 2,247,529 Taylor et al. July 1, 1941 2,255,755 Bell Sept.16, 1941 2,273,752 Frey Feb. 17, 1942 2,419,320 Lohrke Apr. 22, 1947

